“Humans are the only species that willingly deprive themselves from sleep”. Ever since fire was discovered, we have traded off sleep time for other activities - from creating stone tools to partying. As our technology progressed, the list of things to do rather than sleep just got longer. But with sleep deprivation now a growing health problem, could we be reaching our limits? Or is tiredness part of our condition?

In this week’s programme, an evolutionary biologist, a historian and a neuroscientist give us their take on whether we are now any more tired than our ancestors. We hear what makes human sleep unique and how it has evolved in surprising ways. And finally we hear from a woman with a dream – that we may never have to sleep again.

Producer: Estelle Doyle and Sarah Shebbeare Presenter: James Fletcher

(Photo: A woman shows signs of tiredness as she counts ballot cards. Credit: Leon Neal/Getty Images)

China is currently developing the biggest infrastructure initiative of all time. Called the Belt and Road initiative, the trillion dollar plans involve working with other Asian countries to build hundreds of new roads, high speed trains, ports and pipelines across continent to mimic the ancient Silk Road trading routes. The project offers a clear economic opportunity, but the diplomatic ties that form as a result could have the potential to change the current world order.

Presenter: Ruth Alexander Producer: Kate Lamble

(image: Local people control their sheep and goats on the Karakoram highway in northern Pakistan, part of the new Silk Road. Credit: Aamir Queeshi/AFP/ Getty Images)

On 12 June 2017 thousands of protesters took to the streets in over 160 towns and cities across Russia. Opposition leader Alexei Navalny called on people to march against corruption from Kaliningrad in the west to Yuzhno-Sakhalinsk in the east, in bustling cities and significantly, in rural towns where support for President Putin is strong. This is unusual. Protests are usually restricted to the urban elites in Moscow. So who is Navalny and how has he managed to bring so many people out on the streets?

Our expert witnesses assess the strength of the opposition movement in Russia. They explain that the protests reveal a greater threat to Putin. The mobilisation of a young generation who do not believe what they see on state TV and are turning to opposition politics online instead.

Presenter: Ruth Alexander Producers: Phoebe Keane and Estelle Doyle

(Photo: Russian opposition leader Alexei Navalny speaks during a rally in Lyublino, a suburb of Moscow, 20 September 2015. Credit: Getty Images)

When violent jihadis struck London last Saturday, the rolling news networks kicked quickly into action. The story became front-page news around the world and dominated the UK's news media for days, with ever more information on the attack, the victims and the perpetrators. It was shocking, horrific - and perhaps also exactly what the terrorists wanted.

Terrorists rely on the world's media to spread their message of fear and their ideology. Maybe if there was less media coverage of such attacks, it would frustrate the people behind them. We look at four democratic countries where attempts have been made to limit the media impact of terrorism. Drawing on the lessons learnt, how do you report terrorism?

Presenter: Ruth Alexander Producer: Simon Maybin and Phoebe Keane

(Photo: Various newspapers spread out headlining the London Terror attacks)

Many of us find our jobs stressful, underpaid and the hours too long. But few would complain about work being less physically strenuous than in the past. And yet, new research shows that the decline in physical activity at work is key to explaining the obesity epidemic. So - is work now too easy? And if it is, can this be reversed? Producers: Estelle Doyle and Phoebe Keane Presenter: Michael Blastland

(Photo: Office workers at desks using computers in an office. Credit: Getty Images)

Does the experience of poverty actually take a physical toll on your brain? The Inquiry investigates the scientific claims that being poor affects how our brains work.

It's well known that children from poorer backgrounds do worse at school. And adults who are poor are often criticised for making bad life decisions - ones that don't help them in the long-term.

Some say the problems are rooted in the unfair way our society functions. Others argue it's simple genetics. But a growing body of research suggests that something else may be going on too.

The Inquiry assesses the evidence and asks: does poverty change the way we think?

Presenter: Ruth Alexander Producers: Simon Maybin and Phoebe Keane

(Photo: Concept of human intelligence with human brain on blue background. Credit: Shutterstock)

Brexit showed that the issue is now among the most important for British voters. And that’s likely to continue in June’s UK general election, as major parties have made their positions on immigration central to their campaigns. And yet for decades, immigration was a no-go area for mainstream debate. Following racial tensions in the 1960s, it came to be perceived as a proxy for racism. Today it is one of the most salient issues in British politics. What changed?

Producer: Estelle Doyle Presenter: Ruth Alexander

(Photo: Border Force check the passports of passengers arriving at Gatwick Airport in London, England. Credit: Getty images)

Once the richest country in South America, Venezuela is now in deep economic crisis.

Children in school are fainting from hunger; patients are dying from the lack of basic medicine. As prices spiral out of control, cash is carried not in wallets, but in backpacks. Street protests over the crisis are growing in size and frequency - and the government's response becoming ever more authoritarian.

Yet in 1970, Venezuela was among the wealthiest countries in the world. It was held up as a beacon of democracy and stability - an example of a successful developing economy that turned oil resource wealth into riches. So what went wrong? How did Venezuela go from so rich to so poor?

Presenter: Linda Yueh Producer: Simon Maybin

(Photo: A father and daughter rest while someone holds their place before sunrise in a long line to buy basic foodstuffs at a supermarket in San Cristobal, Venezuela. Credit: Getty Images)

Tensions between the US and North Korea are running high. Kim Jong-Un has been testing long-range missiles and nuclear weapons. The Trump administration wants Pyongyang to end its nuclear weapons programmes and has said “all of our options are on the table” in pursuit of that goal. North Korea has said that a "super mighty pre-emptive strike” is planned if the US uses military force against them. But – our question this week – how did this poor and isolated country develop nuclear weapons in the first place?

Presenter: Ruth Alexander

Producers: Kate Lamble, Phoebe Keane and Estelle Doyle

(Photo: North Korean leader Kim Jong Un meets scientists and technicians in the field of researches into nuclear weapons. Credit: Reuters)

Yuval Noah Harari, the author of Sapiens and Homo Deus, explores the long history of inequality – from the Stone Age onwards – and asks whether we are on the brink of creating a huge “economically useless” underclass, unable to keep up with enhanced humans, the owners of increasingly valuable data and, eventually, artificial intelligence.

Presenter: Ruth Alexander Producer: Estelle Doyle Editor: Richard Knight

(Photo: Yuval Noah Harari, Credit: Daniel Thomas Smith)

There is a place on the internet where almost two billion of us regularly go – many of us, every day. Facebook: the social network which Mark Zuckerberg started in his university dorm room and which has grown, in a little over a decade, into one of the most valuable companies in the world. But what does Facebook’s lines of computer code do with the data we give it – and what could it do in the future? Just how powerful is Facebook's algorithm? The answer will surprise you.

Producers: Estelle Doyle and Sarah Shebbeare Editor: Richard Knight

(Photo: Facebook CEO Mark Zuckerberg delivers a keynote address during the Facebook f8 conference in San Francisco, California. Credit: Getty Images)

In 2014 marijuana was legalised for recreational use in Colorado and Washington states in the US. Oregon, Alaska, California, Nevada and Massachusetts have all followed. These votes were the result of fierce campaigns. Activists argued that changing the law would eliminate the black market in marijuana; creating a legitimate, taxable industry and allowing the police to focus on more serious crime. Opponents feared more people would become cannabis addicts and predicted an uptick in health problems and robberies. So – three years in – what happened?

Presenter: Ruth Alexander Producers: Kate Lamble and Phoebe Keane

(Photo: Jars full of medical marijuana are seen at Sunset Junction medical marijuana dispensary in Los Angeles, California. Credit: Getty Images)